1. Technical Field
The present invention relates to the field of bonding materials using solvents and, in particular, to methods for using solvents to bond porous flexible membranes to rigid materials.
2. Discussion of Related Art
Porous flexible membranes have broad technical applications including, for example, gas separation, particle filtration, reverse osmosis, water purification, fuel cell, and flow cell battery technologies. In such applications, porous flexible membrane materials are often used in conjunction with structures made of rigid materials. Therefore, porous flexible membranes are commonly bonded or compressively sealed with rigid structures.
In certain applications, porous flexible membranes are utilized in an aqueous solution. For example, in a reduction-oxidation (redox) flow battery or redox flow cell, two-half cells may be separated by a porous flexible ion-exchange membrane (IEM), through which ions are transferred during a redox reaction. Electrolytes (anolyte and catholyte) are flowed through the half-cells as the redox reaction occurs, often with an external pumping system. In this manner, the porous flexible IEM in a flow cell battery operates in an aqueous electrolyte solution.
To effectively separate the two half-cells of a flow cell battery and to structurally integrate the porous flexible IEM into the battery, the IEM is commonly mounted to a rigid frame. However, porous flexible membrane materials often absorb moisture and expand when wetted. Accordingly, if the IEM is mounted to the rigid frame in a non-aqueous medium and later wetted, the IEM will expand and ripple (i.e., become non-planar) within the frame. In the context of a flow cell battery, this rippling can adversely affect the overall efficiency and performance of the cell.
Therefore, it is desirable to develop methods for bonding porous flexible membranes to rigid materials that reduce the problems associated with the expansion of membranes in aqueous solutions.